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Black Hole Genealogy: Identifying Hierarchical Mergers with Gravitational Waves

Kimball, Chase and Talbot, Colm and Berry, Christopher P. L. and Carney, Matthew and Zevin, Michael and Thrane, Eric and Kalogera, Vicky (2020) Black Hole Genealogy: Identifying Hierarchical Mergers with Gravitational Waves. Astrophysical Journal, 900 (2). Art. No. 177. ISSN 1538-4357.

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In dense stellar environments, the merger products of binary black hole mergers may undergo additional mergers. These hierarchical mergers are naturally expected to have higher masses than the first generation of black holes made from stars. The components of hierarchical mergers are expected to have significant characteristic spins, imprinted by the orbital angular momentum of the previous mergers. However, since the population properties of first-generation black holes are uncertain, it is difficult to know if any given merger is first-generation or hierarchical. We use observations of gravitational waves to reconstruct the binary black hole mass and spin spectrum of a population including the possibility of hierarchical mergers. We employ a phenomenological model that captures the properties of merging binary black holes from simulations of globular clusters. Inspired by recent work on the formation of low-spin black holes, we include a zero-spin subpopulation. We analyze binary black holes from LIGO and Virgo's first two observing runs, and find that this catalog is consistent with having no hierarchical mergers. We find that the most massive system in this catalog, GW170729, is mostly likely a first-generation merger, having a 4% probability of being a hierarchical merger assuming a 5 × 10⁵ M_⊙ globular cluster mass. Using our model, we find that 99% of first-generation black holes in coalescing binaries have masses below 44 M_⊙, and the fraction of binaries with near-zero component spins is less than 0.16 (90% probability). Upcoming observations will determine if hierarchical mergers are a common source of gravitational waves.

Item Type:Article
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URLURL TypeDescription Paper
Kimball, Chase0000-0001-9879-6884
Talbot, Colm0000-0003-2053-5582
Berry, Christopher P. L.0000-0003-3870-7215
Carney, Matthew0000-0002-7952-0476
Zevin, Michael0000-0002-0147-0835
Thrane, Eric0000-0002-4418-3895
Kalogera, Vicky0000-0001-9236-5469
Additional Information:© 2020. The American Astronomical Society. Received 2020 May 11; revised 2020 June 27; accepted 2020 July 10; published 2020 September 14. The authors thank Kyle Kremer, Carl Rodriguez, Tom Dent, Mario Spera, and Zoheyr Doctor for their expert advice in constructing this study. The authors are grateful to Riccardo Buscicchio and Ethan Payne for their careful comments on the analysis; Reed Essick for help on calculating detector sensitivities, and Scotty Coughlin for high-performance computing support. This research has made use of data obtained from the Gravitational Wave Open Science Center (, a service of LIGO Laboratory, the LIGO Scientific Collaboration and the Virgo Collaboration. LIGO is funded by the US National Science Foundation (NSF). Virgo is funded by the French Centre National de Recherche Scientifique (CNRS), the Italian Istituto Nazionale della Fisica Nucleare (INFN) and the Dutch Nikhef, with contributions by Polish and Hungarian institutes. This work is supported by the NSF Grant PHY-1607709 and through the Australian Research Council (ARC) Centre of Excellence CE170100004. C.K. is supported supported by the National Science Foundation under grant DGE-1450006. C.P.L.B. is supported by the CIERA Board of Visitors Research Professorship. E.T. is supported through ARC Future Fellowship FT150100281 and CE170100004. This research was supported in part through the computational resources from the Grail computing cluster at Northwestern University—funded through NSF PHY-1726951—and staff contributions provided for the Quest high performance computing facility at Northwestern University, which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. The authors are grateful for computational resources provided by the LIGO Laboratory and supported by NSF Grants PHY-0757058 and PHY-0823459. This document has been assigned LIGO document number LIGO-P2000131.
Funding AgencyGrant Number
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Istituto Nazionale di Fisica Nucleare (INFN)UNSPECIFIED
Dutch National Institute for Subatomic PhysicsUNSPECIFIED
Australian Research CouncilCE170100004
NSF Graduate Research FellowshipDGE-1450006
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)UNSPECIFIED
Australian Research CouncilFT150100281
Northwestern UniversityUNSPECIFIED
Subject Keywords:Gravitational wave sources ; Gravitational wave astronomy ; Astrophysical black holes ; Hierarchical models
Other Numbering System:
Other Numbering System NameOther Numbering System ID
LIGO DocumentP2000131
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Gravitational wave sources (677); Gravitational wave astronomy (675); Astrophysical black holes (98); Hierarchical models (1925)
Record Number:CaltechAUTHORS:20200914-111809827
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Official Citation:Chase Kimball et al 2020 ApJ 900 177
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105376
Deposited By: George Porter
Deposited On:14 Sep 2020 22:28
Last Modified:14 Sep 2020 22:28

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